2025-10-29: Agentic Chat for gitlab.com/gitlab-com is throwing a persistent error

Agentic Chat for gitlab.com/gitlab-com is throwing a persistent error (Severity 3 (Medium))

Problem: Deployment mismatches between frontend and backend caused persistent errors in Agentic Chat for gitlab.com/gitlab-com.

Impact: Agentic Chat for gitlab.com/gitlab-com showed persistent errors for users until mitigation steps were taken. The issue was limited to this group and did not propagate to wider production.

Causes: A recent merge request introduced a new GraphQL schema field, leading to a deployment mismatch between the frontend and backend.

Response strategy: We drained the canary environment to stop problematic backend requests and prioritized a revert of the merge request with expedited approval and deployment. Chat is now loading correctly for the affected group.

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This ticket was created to track INC-5308, by incident.io 🔥